In recent years, there has been expectation of an increase in demand for purchase of a digital television because analog television broadcasting would be replaced with digital television broadcasting. In expectation of such demand, various manufacturers have developed and sold a variety of digital televisions.
Some of digital television products which have been recently on the market are of a high-end model, such as a product which is capable of displaying a 3D image, a product employing a large display panel, and a product employing a large number of tuners. Note, however, that one of the most important subjects in development of digital televisions is improvement in video quality, irrespective of whether the digital televisions are low-end products or high-end products.
There are various techniques for improving video quality. One of such techniques is luminance correction processing carried out by an image processing device described in Patent Literature 1. This luminance correction technique is specifically described below with reference to FIG. 12 and FIG. 13. FIG. 12 is a block diagram schematically illustrating a configuration of the image processing device described in Patent Literature 1. FIG. 13 is a view showing (i) a luminance histogram is prepared by the image processing device of Patent Literature 1 on the basis of an input image which is a luminance correction target, and (ii) a function graph showing a relationship between a luminance value of each pixel of the input image and a luminance value of each pixel of an output image which is outputted from the image processing device.
The image processing device of Patent Literature 1 includes (i) a luminance distribution information preparation section for preparing a luminance histogram on the basis of a luminance value of each pixel of the input image and (ii) an amplification rate determining section for determining, for each luminance range, an amplification rate so that a relatively-large amplification rate is assigned to a class (luminance range) having a large frequency (a large number of pixels). An image processing section of the image processing device carries out luminance correction with respect to an input image on the basis of the amplification rate determined for each luminance range. In other words, the image processing section carries out luminance correction with respect to an input image so that an output image has an increase in difference between a maximum luminance and a minimum luminance in a pixel region constituted by pixels each having a luminance belonging to a luminance range having a large frequency.
The image processing device described in Patent Literature 1 causes a display device to display the output image that has been subjected to the luminance correction processing so that an image displayed on the display device can have a marked difference between a maximum luminance and a minimum luminance in a relatively wide pixel region in a display screen, as compared to a case where an input image is displayed as an output image on the display device without being subjected to the luminance correction processing. For example, in a case where a luminance histogram shown in a lower part of FIG. 13 is obtained based on an input image, the luminance correction processing causes a difference between a maximum luminance and a minimum luminance in a wide pixel region to change from A to A′ (>A), as shown in a graph in an upper part of FIG. 13. That is, the image processing device described in Patent Literature 1 allows a user to view images which are higher in contrast.